Immunofiltration: A methodology for preconcentration and determination of organic pollutants

A new concentration procedure using an immunofiltration-based method is des cribed. The approach enables quantitative determination of organic pollutan ts by filtering large volumes of sample through a poly(vinylidene difluorid e) membrane where antibodies have been immobilized by passive adsorption. T he analysis is based on a sequential competitive enzyme immunoassay, A wide range of sample volumes have been tested (0.2-5.0 mt) for each type of ant ibody. The improvement on the assay sensitivity and specificity achieved by means of this concentration procedure is discussed, Using this technique a nd the insecticide carbaryl as a model analyte, a concentration factor of a t least 13 and a limit of detection of 4.75 ng/L are accomplished. The suit ability of this methodology is demonstrated by the quantification of the in secticide in several types of water samples (bottled, estuarine, and physio logical-saline solutions) with recoveries ranging between 102 and 111%. Thi s method has proved to concentrate carbaryl directly, in an accurate way, f or residue analysis without using organic solvents or any extraction proces s, Furthermore, this procedure offers the advantages of carrying out in the same system both preconcentration and quantitative determination of the an alyte.